# Deployment bootstrap

ZDDC tools (archive, transmittal, classifier, mdedit, landing) are single-file
HTML bundles. The bootstrap pattern lets you install once on a deployment and
update by editing a few lines, without re-uploading multi-megabyte HTML files.

## The two-level model

A typical `zddc-server` deployment looks like this:

```
<ZDDC_ROOT>/
  index.html                # landing tool (or bootstrap)
  archive.html              # archive tool (or bootstrap; site-wide channel switch lives here)
  transmittal.html
  classifier.html
  mdedit.html
  <project-A>/
    archive.html            # level-1 bootstrap → fetches ../archive.html
    transmittal.html
    classifier.html
    mdedit.html
    <project files…>
  <project-B>/
    archive.html            # level-1 bootstrap (or pinned to a specific version)
    …
```

- **Level-1 stubs** at `<project>/<tool>.html` always fetch the same-origin
  `../<tool>.html`. They never touch `zddc.varasys.io`. Install them once;
  they don't need to change.
- **At deployment root** (`<ZDDC_ROOT>/<tool>.html`), put either:
  - the actual built tool HTML — fully self-contained install, no external
    dependencies; or
  - a level-2 bootstrap — fetches a specific channel or pinned version from
    `https://zddc.varasys.io/releases/<tool>_<channel|v…>.html`.

The site administrator switches the whole site to a channel by replacing
the file at `<ZDDC_ROOT>/<tool>.html` with the matching level-2 stub from
`track-<channel>.zip`. A single project can override one tool by editing
just `<project-X>/<tool>.html` (replace the relative `upstream` URL with an
absolute zddc.varasys.io URL).

## Why two levels

The level-1 stubs let projects share a single source of truth for "which
build of the archive tool runs here." Switching channels is one file change
at the root; pinning a single project is one file change in that directory.

`document.write()` chains across both levels: level-1 fetches and writes,
the new document's level-2 script runs and writes again, the third write
is the actual tool. Origin stays at the deployment domain throughout, so
File System Access API, `crypto.subtle`, and `localStorage` all work and
preferences stay scoped to the deployment.

## Pinning options

There are two ways to choose a version: edit the stub for a permanent
pin, or pass a `?v=` URL parameter for a per-request override.

### 1. Permanent pin (edit the stub)

Each stub has one `fallback`/`upstream` constant. Edit it once and the
choice sticks for everyone using that file.

| URL                                                              | Behavior                                |
|------------------------------------------------------------------|-----------------------------------------|
| `https://zddc.varasys.io/releases/<tool>_latest.html`            | current stable; auto-updates within stable |
| `https://zddc.varasys.io/releases/<tool>_beta.html`              | latest beta build (mutable)             |
| `https://zddc.varasys.io/releases/<tool>_alpha.html`             | latest alpha build (mutable)            |
| `https://zddc.varasys.io/releases/<tool>_v1.2.3.html`            | pinned to exact stable version          |

### 2. Per-request `?v=` parameter

Both stub levels honor a `?v=` URL parameter. The parameter survives the
`document.write()` chain, so it flows through level-1 → level-2 →
upstream automatically.

| URL parameter                  | Behavior                                              |
|--------------------------------|-------------------------------------------------------|
| `?v=0.0.4` (or `?v=v0.0.4`)    | tries `<tool>_v0.0.4.html` locally, then upstream     |
| `?v=alpha`                     | switches to alpha channel                             |
| `?v=beta`                      | switches to beta channel                              |
| `?v=latest`                    | latest stable                                         |
| (omitted)                      | the default baked into the stub                       |

When level-1 has `?v=…`, it tries `../<tool>_<suffix>.html` first (useful
when the admin has staged specific versions locally) and falls back to
`../<tool>.html` if 404 — which then forwards the parameter via level-2
if one is installed. So the same URL works whether the version is
staged locally, served by a level-2 stub, or both.

Stable releases are immutable. Alpha and beta channel files are
overwritten in place each time their channel is rebuilt; expect them to
change without notice. The build label rendered on the tool page tells
you what you are running (date + commit SHA for alpha/beta, version
number for stable).

## Auditing what's installed

Every stub contains a `fallback` (level-1) or `upstream` (level-2)
constant. To see what each tool / project on the deployment points at:

```sh
grep -rn "fallback\|upstream" <ZDDC_ROOT>
```

## CORS prerequisite (level-2 only)

A level-2 fetch is cross-origin (deployment → `zddc.varasys.io`). The
upstream must serve `Access-Control-Allow-Origin: *` (or a list including
your deployment origin) on the released HTML files. Verify with:

```sh
curl -I https://zddc.varasys.io/releases/archive_latest.html | grep -i access-control
```

Level-1 fetches are same-origin so no CORS is involved.

## Templates

`level1.html.tmpl` and `level2.html.tmpl` are the source of truth. The
project's top-level `build.sh` substitutes `{{TOOL}}`, `{{TOOL_TITLE}}`,
and `{{CHANNEL}}` to produce the per-tool stubs that ship in
`install.zip` and `track-<channel>.zip`.